Helmet



FIG. 1 is a rear perspective view of a helmet showing our new design;

FIG. 2 is a side elevational view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a top plan view thereof;

FIG. 5 is a bottom plan view thereof; and,

FIG. 6 is a rear elevational view thereof.

The person shown in broken lines in FIG. 1 denotes the nature and environmental use of the design and is not part of the design. 

The ornamental design for a helmet, as shown and described. 